AS four teenagers were jailed today for the killing of a vulnerable man with learning difficulties in Greenford in February, the victim’s mother spoke of the anguish the family had suffered.

Donna Mayley said: "The loss of our lovely Dean has ripped our family apart. It is so hard to comprehend that we will never see him again.

"As his Mum, I have not been able to grieve for my son or even talk about this horrific ordeal as my two eldest children, Sam and Laura, suffer from learning disabilities.

“I have been unable to tell them the truth about what happened to their little brother. My children become distressed when I begin to show my emotions.

"Sam was recently hospitalised as he had a psychotic breakdown and needed to be given stronger medication. He cannot understand how he has lost his father and little brother in the space of eight months.

"Laura has started to have violent outbursts, pulling her hair and is severely distressed as she misses her brother terribly.

“Sometimes she sits in his room for hours on end, wishing him home. Laura is being seen by a counsellor but due to her learning disability, it is not having the desired effect on her.

“She knew Dean was fit and healthy and cannot take it in that he has gone.

“I have to lie to my children every day as they would not understand that someone could hurt another human being in this way. I feel I am living a nightmare every day of my life.

"My Dean had only just started travelling alone. He used to travel around with his dad up until his dad passed away in June 2013.

“Dean would make the simple trip from our home to his uncle's house in Greenford. He was murdered for nothing at all.

“Our family will never be the same again. The youngest has had his life cut short for no reason and we will all struggle to come to terms with this for the rest of our lives."

Today (Thursday) at the Old Bailey, Jamal Jones, 17, of Newport Road, Acton, was sentenced to 15 years for murder.

Michael Mensah, 18, of Brants Walk, Greenford, was sentenced to 15 years for manslaughter and nine years for attempted robbery, to run concurrently.

He also received two years for robbery after being found guilty of robbing a 15-year-old boy in a separate incident.

Miguel Leiba, 17, of Framfield Road, Hanwell, was sentenced to 14 years for manslaughter and eight years for attempted robbery to run concurrently.

Ryan Beresford, 19, of Winchester Street, Acton, was sentenced to 15 years for manslaughter and nine years for attempted robbery, to run concurrently.

All four were convicted for their involvement in the death of Dean Mayley, who was 24 but had a mental age of nine due to a brain disorder.

They were found guilty on Thursday, August 28, following a hearing at the Old Bailey.

Det Insp Mark Lawson said: "The defendants were a team of robbers who, armed with a knife, were scouring the area that day looking for someone to rob.

"They had not a moment's hesitation in using that knife when Dean didn't immediately hand over his property. The knife was plunged into his heart. There could be no doubt of the defendants' intentions."

Dean, who lived in Northolt, was walking home along Ruislip Road, Greenford, when the four defendants spotted him. They were out in Mensah's Fiat Punto looking for likely victims to rob at knifepoint.

It is thought Dean, who suffered from microcephaly, caught their eye due to his distinctive North Face jacket and because he was alone.

They pulled over and Jones, Leiba and Beresford got out, Jones armed with a knife.

Jones approached Dean while the others went past him, blocking any chance of him escaping.

It's thought Dean's condition meant he didn't readily understand what was happening and he didn't hand over any of his property during the confrontation.

Jones then stabbed him, straight into his heart, before all three ran off back to the car.

Dean staggered into the street and collapsed. Passers-by went to help him and police and the London Ambulance Service were called.

Despite their best efforts, he died less than two hours later at St Mary's Hospital.

Mensah and Jones were arrested at their homes and Beresford and Leiba two days later after detectives released CCTV images of them. They handed themselves in to Colindale police station.